If it sounds better with the factory speakers, chalk it up to a lesson learned, then put them on Ebay.
Listen to the speakers. Adjust the tone controls to get it as close as you can to what you want, without the bass. Are the highs nice and clear, or are they fuzzy and indistinct?
Is the midrange (vocals, guitar) solid and full-sounding?
If you can answer positively to both questions, then install the sub to fill in the bass.
If not, put the factory speakers back in, then install the sub.
James 1:25 Ordered from Faulkner Chevy #NKCF02 1100 5/8/9 2000, 3300 7/16/9 TPW 7/20,GOT MY (low) VIN! 4000 7/24/9 ,Picked up 8/7/9!!! Signed Litho #45. Car signed by FBodfather 2011. Service: Jennings Chevy in PA. We don't "drift", kiddies... we POWER SLIDE!
MOTM/COTM Sept 2012 Pro Patria Vigilans
Click the pic.. I don't tolerate fools.